La^3＋对过氧化氢酶电化学和生物电催化活性的影响

Effect of La^(3+) on Electrochemical and Bioelectrocatalytic Activity of Catalase

本文研究了La^3+对过氧化氢酶(CAT)的直接电化学反应活性和对H2O2还原的生物电催化活性的影响。发现当La^3+浓度低时,La^3+能提高CAT的直接电化学反应活性和对H_2O_2还原的电催化活性。当La^3+浓度高时,La^3+会降低CAT的直接电化学反应活性和对H_2O_2还原的电催化活性。这是由于La^3+能与CAT的肽链上的氨基酸残基发生作用而使肽链构象发生变化,导致血红素结构发生变化。当La^3+浓度低时,La^3+能使血红素的非平面性增加,活性中心Fe!的暴露程度增加,因此,低浓度的La^3+能增加CAT的电化学和生物电催化活性,而高浓度的La^3+却会使血红素的非平面性降低,活性中心Fe!的暴露程度降低,因此,降低了CAT的电化学和生物电催化活性。

The effect of La^3＋ on the electrochemical activity and the bioelectrocatalytic activity of catalase （CAT） for the H2O2 reduction was investigated. It is found that when the La^3＋ concentration is low La^3＋ can increase the electrochemical and bioelectrocatalytic activity of CAT. When the La^3＋ concentration is high La^3＋ can decrease the electrochemical and bioelectrocatalytic activity of CAT. This is due to that La^3＋ can interact with amino acid residues in the peptide of CAT. The interaction would lead to the change in the conformation of the peptide and then the change in the structure of the heme group. When the La^3＋ concentration is low, La^3＋ can increase the non-planarity of the heme group, leading to the increase in the exposure extent of the heme active center, Fe（Ⅱ）. Thus, La^3＋ at the low concentration can increase the electrochemical and the bioelectrocatalytic activity of CAT. When the La^3＋ concentration is high, La^3＋ can decrease the non-planarity of the heme group, leading to the decrease in the exposure extent of Fe（Ⅱ）. Thus, La^3＋ at the high concentration can decrease the electrochemical and bioelectrocatalytic activity of CAT.